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Cat. No.: LLAKW8-100 (for 100T)

Description

L-Lactate Assay Kit with WST-8 is a colorimetric assay kit based on the WST-8 reaction, designed to rapidly and sensitively detect L-lactate and L-lactate salts in biological fluids such as serum or plasma, cell or tissue samples, and fermented food products such as milk.

Lactic acid (LA) is a hydroxycarboxylic acid, chemically known as 2-hydroxypropionic acid, α-hydroxypropionic acid, or propionic acid, with the molecular formula C3H6O3 and a molecular weight of 90.08. Due to its asymmetric carbon atom (chiral carbon), lactic acid typically exists in two optical isomer forms: D-lactic acid (D(-)-Lactate) and L-lactic acid (L(+)-Lactate). When mixed in equal proportions, it forms racemic DL-lactic acid.

L-lactic acid is produced by the brain, red blood cells, skeletal muscle, and intestines and is metabolized by the liver, heart, and kidneys. Almost all lactic acid produced in the human body is L-lactic acid. The liver primarily clears L-lactic acid from the blood, but hypoxia, acidosis, oxygen supply issues, and low perfusion can impair the liver’s uptake of L-lactic acid. The concentration of L-lactic acid in the blood is crucial for diagnosing patient conditions during intensive care and surgery. High L-lactic acid concentrations can indicate diseases such as intestinal infarction, cardiac arrest, and sepsis. The concentration of L-lactic acid in saliva can serve as an early diagnostic indicator for cystic fibrosis. L-lactic acid is also a biomarker for energy metabolism, brain, and tumor cells. In the food industry, L-lactic acid is used during fermentation as an indicator of quality, freshness, flavor, stability, and storage life.

D-lactic acid primarily originates from gastrointestinal bacteria and exogenous intake and is produced in very low amounts in tissues. Due to the metabolism of methylglyoxal (MGO), it usually exists at nanomolar concentrations in mammalian blood. In the food industry, D-lactic acid can be produced by lactic acid bacteria and is found in many dairy beverages and pickled products such as yogurt, pickled vegetables, and cured meats. In some gastrointestinal diseases, the production of bacterial D-lactic acid and its absorption from the intestine into the bloodstream increases, leading to intestinal barrier damage and inflammation. Excessive accumulation of D-lactic acid in the body can lead to potentially life-threatening D-lactic acidosis or D-lactate encephalopathy. D-lactic acidosis is a rare neurological syndrome mainly occurring in patients with short bowel syndrome or after jejunoileal bypass surgery. Symptoms usually appear after ingesting high carbohydrates, which are fermented by abnormal microbiota in the colon to produce excess D-lactic acid. Therefore, determining D-lactic acid levels is significant for monitoring bacterial infections, short bowel syndrome, sepsis, and can serve as a marker of intestinal barrier integrity.

Components

• Buffer A for Metabolic Assay
• Lactate Assay Buffer
• Enzyme Solution
• Substrate
• WST-8
• L-Lactate Standard (100mM)

Principle

L-lactic acid is oxidized to pyruvate by L-lactate dehydrogenase (L-LDH), during which NAD+ is reduced to NADH. The resulting NADH, in the presence of the electron coupling reagent 1-mPMS (1-Methoxy-5-methylphenazinium methyl sulfate), reduces WST-8 to orange formazan, which has an absorption peak around 450nm. The amount of formazan produced in the reaction system is proportional to the amount of L-lactic acid in the sample.

Features

• This kit offers high sensitivity, wide linear range, and low sample usage. It can specifically detect L-lactate without detecting D-lactate. With a sample volume of 50μl, it can detect L-lactate concentrations as low as 20µM, maintaining a good linear relationship within the concentration range of 0.02mM to 1mM (1nmol to 50nmol). The kit includes a L-lactate standard solution, which allows for the calculation of L-lactate content in samples by setting up a standard curve. If the sample volume is low or the L-lactate content in the sample is low, the Amplex Red L-Lactate Assay Kit with higher sensitivity can be used. For D-lactate detection, you can use the D-Lactate Assay Kit with WST-8.
• This kit offers versatile lysis buffer for detection. The Buffer A for Metabolic Assay provided with this kit can be used to lyse cells or tissue samples, which can then be analyzed using other metabolic assay kits from our range that also use Buffer A for Metabolic Assay. This provides strong compatibility and can also be used for protein concentration measurement, SDS-PAGE, or Western blotting for easily soluble proteins.
• The kit is flexible, fast, and widely applicable. It can be used to analyze biological fluids such as serum, plasma, and urine from mice, rats, humans, as well as cell culture supernatants, tissue, or cell samples. The entire process takes approximately 0.5-1 hour to complete. The kit is suitable for both small sample analyses and high-throughput screening automation systems.

Storage

Store at -20ºC. Valid for one year. WST-8 should be protected from light.

Precautions

• This kit can only detect L-lactate and not D-lactate. For D-lactate detection, you can use D-Lactate Assay Kit with WST-8.
• Buffer A for Metabolic Assay and Lactate Assay Buffer need to be completely thawed and equilibrated to room temperature before use, otherwise, the detection results may be affected. Other reagents should be used on ice.
• When removing the substrate from -20ºC, some precipitation may occur during thawing. Once equilibrated to room temperature, the precipitates will redissolve and will not affect the detection results.
• Serum, plasma, and other samples stored at 4ºC should not be stored for more than 2 weeks, as this may affect the accuracy of the detection results. Typically, serum samples should be stored at -20ºC or -80ºC.
• To minimize errors from the background of diluents, the diluents for samples and standards should be selected based on the sample type. For cell or tissue lysate samples, Buffer A for Metabolic Assay should be used for dilution. For blood and other samples, Lactate Assay Buffer should be used for dilution.
• This product is for scientific research use by professionals only and is not intended for clinical diagnosis or treatment, food or drug use, or to be stored in a regular residence.
• For your safety and health, please wear a lab coat and disposable gloves during operation.